A New Miniature Rivuline Fish from the upper Negro River Basin, Northern Brazil (Teleostei, Cypridontiformes, Rivulidae)

Abstract

Rivulus romeri sp.nov. is described from a small stream tributary of Igarapé Iauiari, upper Negro river drainage, Amazonian basin, northern Brazil. It seems to be closely related to R. atratus Garman, 1895 and R. ornatus Garman, 1895 by all sharing apomorphic frontal squamation and head color pattern. It is diagnosed by the long and pointed anal fin of male, also present in R. gransabanae Lasso, Taphorn & Thomerson, 1992, and constitutes the smallest species of the genus. The long and narrow basihyal of R. romeri sp.nov. seems to be unique among congeners.